Mobile network systems using subscriber terminals, such as mobile phones, have already become widespread. In a mobile network, which intermediates mobile phone calls and data transmission and reception, a lot of base stations, which carry out data exchange with mobile phones, are arranged. These base stations have a so-called cellular configuration and form a coverage in which communication with subscriber terminals is provided. Each base station receives transmission data transmitted from subscriber terminals and transmits the received data to a core network via a transmission line. Each base station also transmits data that are received through the core network and the transmission line to subscriber terminals. The core network is connected to external networks, such as the Internet line. As an example, in the LTE (Long Term Evolution), an S1 interface, which links each base station (evolutional Node B (abbreviated as eNB)) with a core system (Evolved Packet Core: EPC), or the like is defined by 3GPP (NPL 1). For a link between the core network and a base station, a long-distance and large-capacity transmission is required. Therefore, a wire communication means, such as optical communication by use of optical fibers, or a high-speed wireless communication means is required to be laid down as a transmission line for the link between the core network and a base station, in general.
Recent years, the OpenFlow technology has been proposed as a network configuration method (NPLs 2 and 3). The OpenFlow technology is a technology that separates a packet transfer function from a routing control function by the opened OpenFlow protocol. An OpenFlow network is configured with an OFS (OpenFlow Switch), which has the packet transfer function, and an OFC (OpenFlow Controller), which has the routing control function. The OFC is capable of centrally controlling a plurality of OFSes.
The OFC registers information on conditions and processing for packet filtering and the like in a flow table of the OFS. The OFS carries out processing, such as data transfer, based on the flow table. A physical port number, transmission source/destination MAC (Media Access Control) addresses, a VLAN (Virtual Local Area Network) ID, transmission source/destination IP (Internet Protocol) addresses, a port number in TCP (Transmission Control Protocol)/UDP (User Datagram Protocol), and the like can be used as conditions in the flow table. Thus, it is possible to carry out control by combining information at Layers 1 to 4.
The OFC is capable of monitoring traffic by acquiring statistical information of the OFS. When the network is disconnected due to a failure of the OFS or the like, the OFC is capable of detecting the disconnection immediately. The OFC is capable of recalculating a path in accordance with detected the disconnection and resetting an alternative path.